Anyone who listened to shortwave radio or was a ham radio operator from the mid 1970s to the late 1980s will be familiar with a sharp, repetitive “rat tat tat tat” noise that permeated the airwaves disrupting communications and television signals the world over. Nicknamed the “Woodpecker”, the signal came from a massive array of antennas hidden deep in the woods—two located near Chernobyl in Russia, and a third one on the Russian Pacific coast, near the island of Sakhalnsk. These antennas formed part of an early warning radar system called Duga, that the Soviets developed to detect incoming ballistic missiles from America.